Hybrid maize plant and seeds (3237)

ABSTRACT

According to the invention, there is provided a hybrid maize plant, designated as 3237, produced by crossing two Pioneer Hi-Bred International, Inc. proprietary inbred maize lines. This invention relates to the hybrid seed 3237, the hybrid plant produced from the seed, and variants, mutants, and trivial modifications of hybrid 3237.

FIELD OF THE INVENTION

This invention is in the field of maize breeding, specifically relatingto a hybrid maize line designated 3237.

BACKGROUND OF THE INVENTION Plant Breeding

Field crops are bred through techniques that take advantage of theplant's method of pollination. A plant is self-pollinated if pollen fromone flower is transferred to the same or another flower of the sameplant. A plant is cross-pollinated if the pollen comes from a flower ona different plant.

Plants that have been self-pollinated and selected for type for manygenerations become homozygous at almost all gene loci and produce auniform population of true breeding progeny. A cross between twodifferent homozygous lines produces a uniform population of hybridplants that may be heterozygous for many gene loci. A cross of twoplants each heterozygous at a number of gene loci will produce apopulation of hybrid plants that differ genetically and will not beuniform.

Maize (Zea mays L.), often referred to as corn in the United States, canbe bred by both self-pollination and cross-pollination techniques. Maizehas separate male and female flowers on the same plant, located on thetassel and the ear, respectively. Natural pollination occurs in maizewhen wind blows pollen from the tassels to the silks that protrude fromthe tops of the ears.

The development of a hybrid maize variety involves three steps: (1) theselection of plants from various germplasm pools for initial breedingcrosses; (2) the selfing of the selected plants from the breedingcrosses for several generations to produce a series of inbred lines,which, although different from each other, breed true and are highlyuniform; and (3) crossing the selected inbred lines with unrelatedinbred lines to produce the hybrid progeny (F₁). During the inbreedingprocess in maize, the vigor of the lines decreases. Vigor is restoredwhen two different inbred lines are crossed to produce the hybridprogeny (F₁). An important consequence of the homozygosity andhomogeneity of the inbred lines is that the hybrid created by crossing adefined pair of inbreds will always be the same. Once the inbreds thatcreate a superior hybrid have been identified, a continual supply of thehybrid seed can be produced using these inbred parents and the hybridcorn plants can then be generated from this hybrid seed supply.

Large scale commercial maize hybrid production, as it is practicedtoday, requires the use of some form of male sterility system whichcontrols or inactivates male fertility. A reliable method of controllingmale fertility in plants also offers the opportunity for improved plantbreeding. This is especially true for development of maize hybrids,which relies upon some sort of male sterility system. There are severaloptions for controlling male fertility available to breeders, such as:manual or mechanical emasculation (or detasseling), cytoplasmic malesterility, genetic male sterility, gametocides and the like.

Hybrid maize seed is typically produced by a male sterility systemincorporating manual or mechanical detasseling. Alternate strips of twoinbred varieties of maize are planted in a field, and the pollen-bearingtassels are removed from one of the inbreds (female). Providing thatthere is sufficient isolation from sources of foreign maize pollen, theears of the detasseled inbred will be fertilized only from the otherinbred (male), and the resulting seed is therefore hybrid and will formhybrid plants.

The laborious, and occasionally unreliable, detasseling process can beavoided by using cytoplasmic male-sterile (CMS) inbreds. Plants of a CMSinbred are male sterile as a result of factors resulting from thecytoplasmic, as opposed to the nuclear, genome. Thus, thischaracteristic is inherited exclusively through the female parent inmaize plants, since only the female provides cytoplasm to the fertilizedseed. CMS plants are fertilized with pollen from another inbred that isnot male-sterile. Pollen from the second inbred may or may notcontribute genes that make the hybrid plants male-fertile. Usually seedfrom detasseled fertile maize and CMS produced seed of the same hybridare blended to insure that adequate pollen loads are available forfertilization when the hybrid plants are grown.

There are several methods of conferring genetic male sterilityavailable, such as multiple mutant genes at separate locations withinthe genome that confer male sterility, as disclosed in U.S. Pat. Nos.4,654,465 and 4,727,219 to Brar et al. and chromosomal translocations asdescribed by Patterson in U.S. Pat. Nos. 3,861,709 and 3,710,511. Theseand all patents referred to are incorporated by reference. In additionto these methods, Albertsen et al., of Pioneer Hi-Bred, U.S. patentapplication Ser. No. 07/848,433, have developed a system of nuclear malesterility which includes: identifying a gene which is critical to malefertility; silencing this native gene which is critical to malefertility; removing the native promoter from the essential malefertility gene and replacing it with an inducible promoter; insertingthis genetically engineered gene back into the plant; and thus creatinga plant that is male sterile because the inducible promoter is not "on"resulting in the male fertility gene not being transcribed. Fertility isrestored by inducing, or turning "on", the promoter, which in turnallows the gene that confers male fertility to be transcribed.

There are many other methods of conferring genetic male sterility in theart, each with its own benefits and drawbacks. These methods use avariety of approaches such as delivering into the plant a gene encodinga cytotoxic substance associated with a male tissue specific promoter oran antisense system in which a gene critical to fertility is identifiedand an antisense to that gene is inserted in the plant (see:Fabinjanski, et al. EPO 89/3010153.8 publication no. 329,308 and PCTapplication PCT/CA90/00037 published as WO 90/08828).

Another system useful in controlling male sterility makes use ofgametocides. Gametocides are not a genetic system, but rather a topicalapplication of chemicals. These chemicals affect cells that are criticalto male fertility. The application of these chemicals affects fertilityin the plants only for the growing season in which the gametocide isapplied (see Carlson, Glenn R., U.S. Pat. No. 4,936,904). Application ofthe gametocide, timing of the application and genotype specificity oftenlimit the usefulness of the approach.

The use of male sterile inbreds is but one factor in the production ofmaize hybrids. The development of maize hybrids requires, in general,the development of homozygous inbred lines, the crossing of these lines,and the evaluation of the crosses. Breeding programs combine the geneticbackgrounds from two or more inbred lines or various other broad-basedsources into breeding pools from which new inbred lines are developed byselfing and selection of desired phenotypes. The new inbreds are crossedwith other inbred lines and the hybrids from these crosses are evaluatedto determine which of those have commercial potential.

There are many important factors to be considered in the art of plantbreeding, such as the ability to recognize important morphological andphysiological characteristics, the ability to design evaluationtechniques for genotypic and phenotypic traits of interest, and theability to search out and exploit the genes for the desired traits innew or improved combinations.

The objective of commercial maize hybrid line development programs is todevelop new inbred lines to produce hybrids that combine to produce highgrain yields and superior agronomic performance. The primary traitbreeders seek is yield. However, many other major agronomic traits areof importance in hybrid combination and have an impact on yield orotherwise provide superior performance in hybrid combinations. Suchtraits include percent grain moisture at harvest, relative maturity,resistance to stalk breakage, resistance to root lodging, grain quality,and disease and insect resistance. In addition, the lines per se musthave acceptable performance for parental traits such as seed yields,kernel sizes, pollen production, all of which affect ability to provideparental lines in sufficient quantity and quality for hybridization.These traits have been shown to be under genetic control and many if notall of the traits are affected by multiple genes.

Pedigree Breeding

The pedigree method of breeding is the mostly widely used methodologyfor new hybrid line development.

In general terms this procedure consists of crossing two inbred lines toproduce the non-segregating F₁ generation, and self pollination of theF₁ generation to produce the F₂ generation that segregates for allfactors for which the inbred parents differ. An example of this processis set forth below. Variations of this generalized pedigree method areused, but all these variations produce a segregating generation whichcontains a range of variation for the traits of interest.

EXAMPLE 1

Hypothetical example of pedigree breeding program

Consider a cross between two inbred lines that differ for alleles at sixloci. The parental genotypes are:

    Parent 1 A b C d e F/A b C d e F

    Parent 2 a B c D E f/a B c D E f

the F₁ from a cross between these two parents is:

    F.sub.1 A b C d e F/a B c D E f

Selfing F₁ will produce an F₂ generation including the followinggenotypes:

    ______________________________________                                        A B c D E f/a b C d e F                                                       A B c D e f/a b C d E F                                                       A B c D e f/a b C d e F                                                       .                                                                             .                                                                             ______________________________________                                    

The number of genotypes in the F₂ is 3⁶ for six segregating loci (729)and will produce (2⁶)-2 possible new inbreds, (62 for six segregatingloci).

Each inbred parent which is used in breeding crosses represents a uniquecombination of genes, and the combined effects of the genes define theperformance of the inbred and its performance in hybrid combination.There is published evidence (Smith, O. S., J. S. C. Smith, S. L. Bowen,R. A. Tenborg and S. J. Wall, TAG 80:833-840 (1990)) that each of thelines are different and can be uniquely identified on the basis ofgenetically-controlled molecular markers.

It has been shown (Hallauer, Amel R. and Miranda, J. B. Fo. QuantitativeGenetics in Maize Breeding, Iowa State University Press, Ames Iowa,1981) that most traits of economic value in maize are under the geneticcontrol of multiple genetic loci, and that there are a large number ofunique combinations of these genes present in elite maize germplasm. Ifnot, genetic progress using elite inbred lines would no longer bepossible. Studies by Duvick and Russell (Duvick, D. N., Maydica37:69-79, (1992); Russell, W. A., Maydica XXIX:375-390 (1983)) haveshown that over the last 50 years the rate of genetic progress incommercial hybrids has been between one and two percent per year.

The number of genes affecting the trait of primary economic importancein maize, grain yield, has been estimated to be in the range of 10-1000.Inbred lines which are used as parents for breeding crosses differ inthe number and combination of these genes. These factors make the plantbreeder's task more difficult. Compounding this is evidence that no oneline contains the favorable allele at all loci, and that differentalleles have different economic values depending on the geneticbackground and field environment in which the hybrid is grown. Fiftyyears of breeding experience suggests that there are many genesaffecting grain yield and each of these has a relatively small effect onthis trait. The effects are small compared to breeders' ability tomeasure grain yield differences in evaluation trials. Therefore, theparents of the breeding cross must differ at several of these loci sothat the genetic differences in the progeny will be large enough thatbreeders can develop a line that increases the economic worth of itshybrids over that of hybrids made with either parent.

If the number of loci segregating in a cross between two inbred lines isn, the number of unique genotypes in the F₂ generation is 3^(n) and thenumber of unique inbred lines from this cross is {(2^(n))-2}. Only avery limited number of these combinations are useful. Only about 1 in10,000 of the progeny from F₂ 's are commercially useful.

By way of example, if it is assumed that the number of segregating lociin F₂ is somewhere between 20 and 50, and that each parent is fixed forhalf the favorable alleles, it is then possible to calculate theapproximate probabilities of finding an inbred that has the favorableallele at {(n/2)+m} loci, where n/2 is the number of favorable allelesin each of the parents and m is the number of additional favorablealleles in the new inbred. See Example 2 below. The number m is assumedto be greater than three because each allele has so small an effect thatevaluation techniques are not sensitive enough to detect differences dueto three or less favorable alleles. The probabilities in Example 2 areon the order of 10⁻⁵ or smaller and they are the probabilities that atleast one genotype with (n/2)=m favorable alleles will exist.

To put this in perspective, the number of plants grown on 60 millionacres (approximate United States corn acreage) at 25,000 plants/acre is1.5×10¹².

EXAMPLE 2

Probability of finding an inbred with m of n favorable alleles.

Assume each parent has n/2 of the favorable alleles and only 1/2 of thecombinations of loci are economically useful.

    ______________________________________                                        No. of   No. of favorable                                                                          No. additional                                           segregating loci                                                                       alleles in Parents                                                                        favorable alleles                                                                         Probability that                             (n)      (n/2)       in new inbred                                                                             genotype occurs*                             ______________________________________                                        20       10          14          3 × 10.sup.-5                          24       12          16          2 × 10.sup.-5                          28       14          18          1 × 10.sup.-5                          32       16          20          8 × 10.sup.-6                          36       18          22          5 × 10.sup.-6                          40       20          24          3 × 10.sup.-6                          44       22          26          2 × 10.sup.-6                          48       24          28          1 × 10.sup.-6                          ______________________________________                                         *Probability that a useful combination exists, does not include the           probability of identifying this combination if it does exist.            

The possibility of having a usably high probability of being able toidentify this genotype based on replicated field testing would be mostlikely smaller than this, and is a function of how large a population ofgenotypes is tested and how testing resources are allocated in thetesting program.

Pioneer research station staff propose about 400 to 500 new inbreds eachyear from over 2,000,000 pollinations. Of those proposed new inbreds,less than 50, and more commonly less than 30, are actually selected forcommercial use.

SUMMARY OF THE INVENTION

According to the invention, there is provided a hybrid maize plant,designated as 3237, produced by crossing two Pioneer Hi-BredInternational, Inc. proprietary inbred maize lines. This invention thusrelates to the hybrid seed 3237, the hybrid plant produced from theseed, and variants, mutants, and trivial modifications of hybrid 3237.This hybrid maize plant is high yielding over a wide range of yieldlevels compared to other hybrids of similar maturity. Hybrid 3237demonstrates above average drought tolerance and excellent rootstrength. Hybrid 3237 demonstrates very good resistance to brittle snap,Gibberella Ear Rot and Corn Lethal Necrosis. It is best adapted for theSouthwestern and Western regions of the United States including TexasHigh Plains, Kansas, Southern Nebraska, Southern Iowa and Missouri.

DEFINITIONS

In the description and examples that follow, a number of terms are usedherein. In order to provide a clear and consistent understanding of thespecification and claims, including the scope to be given such terms,the following definitions are provided. NOTE: ABS is in absolute termsand %MN is percent of the mean for the experiments in which the inbredor hybrid was grown. These designators will follow the descriptors todenote how the values are to be interpreted. Below are the descriptorsused in the data tables included herein.

ANT ROT=ANTHRACNOSE STALK ROT (Colletotrichum graminicola). A 1 to 9visual rating indicating the resistance to Anthracnose Stalk Rot. Ahigher score indicates a higher resistance.

BAR PLT=BARREN PLANTS. The percent of plants per plot that were notbarren (lack ears).

BRT STK=BRITTLE STALKS. This is a measure of the stalk breakage near thetime of pollination, and is an indication of whether a hybrid or inbredwould snap or break near the time of flowering under severe winds. Dataare presented as percentage of plants that did not snap in pairedcomparisons and on a 1 to 9 scale (9=highest resistance) inCharacteristics Charts.

BU ACR=YIELD (BUSHELS/ACRE). Yield of the grain at harvest in bushelsper acre adjusted to 15.5% moisture.

CLN=CORN LETHAL NECROSIS (synergistic interaction of maize chloroticmottle virus (MCMV) in combination with either maize dwarf mosaic virus(MDMV-A or MDMV-B) or wheat streak mosaic virus (WSMV)). A 1 to 9 visualrating indicating the resistance to Corn Lethal Necrosis. A higher scoreindicates a higher resistance.

COM RST=COMMON RUST (Puccinia sorghi). A 1 to 9 visual rating indicatingthe resistance to Common Rust. A higher score indicates a higherresistance.

CRM=COMPARATIVE RELATIVE MATURITY (see PRM).

D/D=DRYDOWN. This represents the relative rate at which a hybrid willreach acceptable harvest moisture compared to other hybrids on a 1-9rating scale. A high score indicates a hybrid that dries relatively fastwhile a low score indicates a hybrid that dries slowly.

D/E=DROPPED EARS. Represented in a 1 to 9 scale in the CharacteristicsChart, where 9 is the rating representing the least, or no, droppedears.

DIP ERS=DIPLODIA EAR MOLD SCORES (Diplodia maydis and Diplodiamacrospora). A 1 to 9 visual rating indicating the resistance toDiplodia Ear Mold. A higher score indicates a higher resistance.

DRP EAR=DROPPED EARS. A measure of the number of dropped ears per plotand represents the percentage of plants that did not drop ears prior toharvest.

D/T=DROUGHT TOLERANCE. This represents a 1-9 rating for droughttolerance, and is based on data obtained under stress conditions. A highscore indicates good drought tolerance and a low score indicates poordrought tolerance.

EAR HT=EAR HEIGHT. The ear height is a measure from the ground to thehighest placed developed ear node attachment and is measured in inches.This is represented in a 1 to 9 scale in the Characteristics Chart,where 9 is highest.

EAR MLD=General Ear Mold. Visual rating (1-9 score) where a "1" is verysusceptible and a "9" is very resistant. This is based on overall ratingfor ear mold of mature ears without determining the specific moldorganism, and may not be predictive for a specific ear mold.

EAR SZ=EAR SIZE. A 1 to 9 visual rating of ear size. The higher therating the larger the ear size.

ECB 1LF=EUROPEAN CORN BORER FIRST GENERATION LEAF FEEDING (Ostrinianubilalis). A 1 to 9 visual rating indicating the resistance topreflowering leaf feeding by first generation European Corn Borer. Ahigher score indicates a higher resistance.

ECB 2IT=EUROPEAN CORN BORER SECOND GENERATION INCHES OF TUNNELING(Ostrinia nubilalis). Average inches of tunneling per plant in thestalk.

ECB 2SC=EUROPEAN CORN BORER SECOND GENERATION (Ostrinia nubilalis). A 1to 9 visual rating indicating post flowering degree of stalk breakageand other evidence of feeding by European Corn Borer, Second Generation.A higher score indicates a higher resistance.

ECB DPE=EUROPEAN CORN BORER DROPPED EARS (Ostrinia nubilalis). Droppedears due to European Corn Borer. Percentage of plants that did not dropears under second generation corn borer infestation.

E/G=EARLY GROWTH. This represents a 1 to 9 rating for early growth,scored when two leaf collars are visible.

EST CNT=EARLY STAND COUNT. This is a measure of the stand establishmentin the spring and represents the number of plants that emerge on perplot basis for the inbred or hybrid.

EYE SPT=Eye Spot (Kabatiella zeae or Aureobasidium zeae). A 1 to 9visual rating indicating the resistance to Eye Spot. A higher scoreindicates a higher resistance.

FUS ERS=FUSARIUM EAR ROT SCORE (Fusarium moniliforme or Fusariumsubglutinans). A 1 to 9 visual rating indicating the resistance toFusarium ear rot. A higher score indicates a higher resistance.

G/A=GRAIN APPEARANCE. Appearance of grain in the grain tank (scored downfor mold, cracks, red streak, etc.).

GDU=Growing Degree Units. Using the Barger Heat Unit Theory, thatassumes that maize growth occurs in the temperature range 50° F.-86° F.and that temperatures outside this range slow down growth; the maximumdaily heat unit accumulation is 36 and the minimum daily heat unitaccumulation is 0. The seasonal accumulation of GDU is a major factor indetermining maturity zones.

GDU PHY=GDU TO PHYSIOLOGICAL MATURITY. The number of growing degreeunits required for an inbred or hybrid line to have approximately 50percent of plants at physiological maturity from time of planting.Growing degree units are calculated by the Barger method.

GDU SHD=GDU TO SHED. The number of growing degree units (GDUs) or heatunits required for an inbred line or hybrid to have approximately 50percent of the plants shedding pollen and is measured from the time ofplanting. Growing degree units are calculated by the Barger Method,where the heat units for a 24-hour period are: ##EQU1##

The highest maximum temperature used is 86° F. and the lowest minimumtemperature used is 50° F. For each inbred or hybrid it takes a certainnumber of GDUs to reach various stages of plant development.

GDU SLK=GDU TO SILK. The number of growing degree units required for aninbred line or hybrid to have approximately 50 percent of the plantswith silk emergence from time of planting. Growing degree units arecalculated by the Barger Method as given in GDU SHD definition.

GIB ERS=GIBBERELLA EAR ROT (PINK MOLD) (Gibberella zeae). A 1 to 9visual rating indicating the resistance to Gibberella Ear Rot. A higherscore indicates a higher resistance.

GLF SPT=Gray Leaf Spot (Cercospora zeae-maydis). A 1 to 9 visual ratingindicating the resistance to Gray Leaf Spot. A higher score indicates ahigher resistance.

GOS WLT=Goss' Wilt (Corynebacterium nebraskense). A 1 to 9 visual ratingindicating the resistance to Goss' Wilt. A higher score indicates ahigher resistance.

GRN APP=GRAIN APPEARANCE. This is a 1 to 9 rating for the generalappearance of the shelled grain as it is harvested based on such factorsas the color of harvested grain, any mold on the grain, and any crackedgrain. High scores indicate good grain quality.

H/POP=YIELD AT HIGH DENSITY. Yield ability at relatively high plantdensities on 1-9 relative rating system with a higher number indicatingthe hybrid responds well to high plant densities for yield relative toother hybrids. A 1, 5, and 9 would represent very poor, average, andvery good yield response, respectively, to increased plant density.

HC BLT=HELMINTHOSPORIUM CARBONUM LEAF BLIGHT (Helminthosporiumcarbonum). A 1 to 9 visual rating indicating the resistance toHelminthosporium infection. A higher score indicates a higherresistance.

HD SMT=HEAD SMUT (Sphacelotheca reiliana). This score indicates thepercentage of plants not infected.

INC D/A=GROSS INCOME (DOLLARS PER ACRE). Relative income per acreassuming drying costs of two cents per point above 15.5 percent harvestmoisture and current market price per bushel.

INCOME/ACRE. Income advantage of hybrid to be patented over other hybridon per acre basis.

INC ADV=GROSS INCOME ADVANTAGE. GROSS INCOME advantage of variety #1over variety #2.

L/POP=YIELD AT LOW DENSITY. Yield ability at relatively low plantdensities on a 1-9 relative system with a higher number indicating thehybrid responds well to low plant densities for yield relative to otherhybrids. A 1, 5, and 9 would represent very poor, average, and very goodyield response, respectively, to low plant density.

MDM CPX=MAIZE DWARF MOSAIC COMPLEX (MDMV=Maize Dwarf Mosaic Virus andMCDV=Maize Chlorotic Dwarf Virus). A 1 to 9 visual rating indicating theresistance to Maize Dwarf Mosaic Complex. A higher score indicates ahigher resistance.

MST=HARVEST MOISTURE. The moisture is the actual percentage moisture ofthe grain at harvest.

MST ADV=MOISTURE ADVANTAGE. The moisture advantage of variety #1 overvariety #2 as calculated by: MOISTURE of variety #2-MOISTURE of variety#1=MOISTURE ADVANTAGE of variety #1.

NLF BLT=Northern Leaf Blight (Helminthosporium turcicum or Exserohilumturcicum). A 1 to 9 visual rating indicating the resistance to NorthernLeaf Blight. A higher score indicates a higher resistance.

PHY CRM=CRM at physiological maturity.

PLT HT=PLANT HEIGHT. This is a measure of the height of the plant fromthe ground to the tip of the tassel in inches. This is represented as a1 to 9 scale, 9 highest, in the Characteristics Chart.

POL SC=POLLEN SCORE. A 1 to 9 visual rating indicating the amount ofpollen shed. The higher the score the more pollen shed.

POL WT=POLLEN WEIGHT. This is calculated by dry weight of tasselscollected as shedding commences minus dry weight from similar tasselsharvested after shedding is complete.

It should be understood that the inbred can, through routinemanipulation of cytoplasmic or other factors, be produced in amale-sterile form. Such embodiments are also contemplated within thescope of the present claims.

POP KIA=PLANT POPULATIONS. Measured as 1000s per acre.

POP ADV=PLANT POPULATION ADVANTAGE. The plant population advantage ofvariety #1 over variety #2 as calculated by PLANT POPULATION of variety#2-PLANT POPULATION of variety #1=PLANT POPULATION ADVANTAGE of variety#1.

PRM=PREDICTED Relative Maturity. This trait, predicted relativematurity, is based on the harvest moisture of the grain. The relativematurity rating is based on a known set of checks and utilizes standardlinear regression analyses and is referred to as the ComparativeRelative Maturity Rating System that is similar to the MinnesotaRelative Maturity Rating System.

PRM SHD=A relative measure of the growing degree units (GDU) required toreach 50% pollen shed. Relative values are predicted values from thelinear regression of observed GDU's on relative maturity of commercialchecks.

PRO=PROTEIN RATING. Rating on a 1 to 9 scale comparing relative amountof protein in the grain compared to hybrids of similar maturity. A "1"score difference represents a 0.4 point change in grain protein percent(e.g., 8.0% to 8.4%).

P/Y=PROTEIN/YIELD RATING. Indicates, on a 1 to 9 scale, the economicvalue of a hybrid for swine and poultry feeders. This takes into accountthe income due to yield, moisture and protein content.

ROOTS (%)=Percent of stalks NOT root lodged at harvest.

R/L=ROOT LODGING. A 1 to 9 rating indicating the level of root lodgingresistance. The higher score represents higher levels of resistance.

RT LDG=ROOT LODGING. Root lodging is the percentage of plants that donot root lodge; plants that lean from the vertical axis as anapproximately 30° angle or greater would be counted as root lodged.

RTL ADV=ROOT LODGING ADVANTAGE. The root lodging advantage of variety #1over variety #2.

S/L=STALK LODGING. A 1 to 9 rating indicating the level of stalk lodgingresistance. The higher scores represent higher levels of resistance.

SCT GRN=SCATTER GRAIN. A 1 to 9 visual rating indicating the amount ofscatter grain (lack of pollination or kernel abortion) on the ear. Thehigher the score the less scatter grain.

SDG VGR=SEEDLING VIGOR. This is the visual rating (1 to 9) of the amountof vegetative growth after emergence at the seedling stage(approximately five leaves). A higher score indicates better vigor.

SEL IND=SELECTION INDEX. The selection index gives a single measure ofthe hybrid's worth based on information for up to five traits. A maizebreeder may utilize his or her own set of traits for the selectionindex. One of the traits that is almost always included is yield. Theselection index data presented in the tables represent the mean valueaveraged across testing stations.

SLF BLT=SOUTHERN LEAF BLIGHT (Heiminthosponum maydis or Bipolarismaydis). A 1 to 9 visual rating indicating the resistance to SouthernLeaf Blight. A higher score indicates a higher resistance.

SLK CRM=CRM at Silking.

SOU RST=SOUTHERN RUST (Puccinia polysora). A 1 to 9 visual ratingindicating the resistance to Southern Rust. A higher score indicates ahigher resistance.

STA GRN=STAY GREEN. Stay green is the measure of plant health near thetime of black layer formation (physiological maturity). A high scoreindicates better late-season plant health.

STAND (%)=Percent of stalks standing at harvest.

STD ADV=STALK STANDING ADVANTAGE. The advantage of variety #1 overvariety #2 for the trait STK CNT.

STK CNT=NUMBER OF PLANTS. This is the final stand or number of plantsper plot.

STK LDG=STALK LODGING. This is the percentage of plants that did notstalk lodge (stalk breakage) as measured by either natural lodging orpushing the stalks and determining the percentage of plants that breakbelow the ear.

STW WLT=Stewart's Wilt (Erwinia stewartii). A 1 to 9 visual ratingindicating the resistance to Stewart's Wilt. A higher score indicates ahigher resistance.

TAS BLS=TASSEL BLAST. A 1 to 9 visual rating was used to measure thedegree of blasting (necrosis due to heat stress) of the tassel at thetime of flowering. A 1 would indicate a very high level of blasting attime of flowering, while a 9 would have no tassel blasting.

TAS SZ=TASSEL SIZE. A 1 to 9 visual rating was used to indicate therelative size of the tassel. The higher the rating the larger thetassel.

TAS WT=TASSEL WEIGHT. This is the average weight of a tassel (grams)just prior to pollen shed.

TEX EAR=EAR TEXTURE. A 1 to 9 visual rating was used to indicate therelative hardness (smoothness of crown) of mature grain. A 1 would bevery soft (extreme dent) while a 9 would be very hard (flinty or verysmooth crown).

TIL LER=TILLERS. A count of the number of tillers per plot that couldpossibly shed pollen was taken. Data is given as a percentage oftillers: number of tillers per plot divided by number of plants perplot.

TST WT (CHARACTERISTICS CHART)=Test weight on a 1 to 9 rating scale witha 9 being the highest rating.

TST WT=TEST WEIGHT (UNADJUSTED). The measure of the weight of the grainin pounds for a given volume (bushel).

TST WTA=TEST WEIGHT ADJUSTED. The measure of the weight of the grain inpounds for a given volume (bushel) adjusted for 15.5 percent moisture.

TSW ADV=TEST WEIGHT ADVANTAGE. The test weight advantage of variety #1over variety #2.

WIN M%=PERCENT MOISTURE WINS.

WIN Y%=PERCENT YIELD WINS.

YLD=YIELD. It is the same as BU ACR ABS.

YLD ADV=YIELD ADVANTAGE. The yield advantage of variety #1 over variety#2 as calculated by: YIELD of variety #1-YIELD variety #2=yieldadvantage of variety #1.

YLD SC=YIELD SCORE. A 1 to 9 visual rating was used to give a relativerating for yield based on plot ear piles. The higher the rating thegreater visual yield appearance.

DETAILED DESCRIPTION OF THE INVENTION

Pioneer Brand Hybrid 3237 is a single cross, yellow endosperm, dentmaize hybrid which is high yielding over a wide range of yield levels.Hybrid 3237 demonstrates above average drought tolerance and excellentroot strength. Hybrid 3237 also exhibits very good resistance to brittlestalk. Hybrid 3237 demonstrates very good resistance to Gibberella EarRot and Corn Lethal Necrosis. Hybrid 3237 is approximately 116 relativematurity based on Comparative Relative Maturity Rating System forharvest moisture of grain.

This hybrid has the following characteristics based on the datacollected primarily at Johnston, Iowa.

                                      TABLE 1                                     __________________________________________________________________________    VARIETY DESCRIPTION INFORMATION                                               VARIETY = 3237                                                                __________________________________________________________________________     1.                                                                              TYPE: (describe intermediate types in Comments section):                    2         1 = Sweet 2 = Dent 3 = Flint 4 = Flour 5 = Pop 6 = Ornamental       2.                                                                              MATURITY:                                                                  DAYS   HEAT                                                                   DAYS   UNITS                                                                   65     1,398                                                                            From emergence to 50% of plants in silk                             64     1,372                                                                            From emergence to 50% of plants in pollen                           6       141                                                                             From 10% to 90% pollen shed                                         70     1,431                                                                            From 50% silk to harvest at 25% moisture                            3.                                                                              PLANT:                                                                                                                Standard                                                                           Sample                                                                   Deviation                                                                          Size                             260.0                                                                             cm  Plant Height (to tassel tip)    19.80                                                                              2                                114.0                                                                             cm  Ear Height (to base of top ear node)                                                                          11.31                                                                              2                                 17.2                                                                             cm  Length of Top Ear Internode     0.85 10                                1      Average Number of Tillers       0.00 2                                 1.0    Average Number of Ears per Stalk                                                                              0.00 2                                 1.0    Anthocyanin of Brace Roots: 1 = Absent 2 = Faint 3 = Moderate                 4 = Dark                                                            4.                                                                              LEAF:                                                                                                                 Standard                                                                           Sample                                                                   Deviation                                                                          Size                              12.0                                                                             cm  Width of Ear Node Leaf          0.85 10                                86.7                                                                             cm  Length of Ear Node Leaf         4.38 10                                6.3                                                                              cm  Number of leaves above top ear  0.14 10                                24.5   Degrees Leaf Angle (measure from 2nd leaf                                                                     2.12 2                                        above ear at anthesis to stalk above leaf)                          3         Leaf Color                                                                              Dark Green                                                                           (Munsell code)                                                                       5GY34                                       1.0       Leaf Sheath Pubescence (Rate on scale from 1 = none to 9 =                    like peach fuzz)                                                    7.5       Marginal Waves (Rate on scale from 1 = none to 9 = many)            8.0       Longitudinal Creases (Rate on scale from 1 = none to 9 =                      many)                                                               5.                                                                              TASSEL:                                                                                                               Standard                                                                           Sample                                                                   Deviation                                                                          Size                           11.7      Number of Primary Lateral Branches                                                                            1.84 10                             70.0      Branch Angle from Central Spike 7.07 2                              8.0       Pollen Shed (rate on scale from 0 = male sterile to 9 = heavy                 shed)                                                               7         Anther    Yellow (Munsell code)                                                                       2.5GY86                                     1         Glume Color                                                                             Light Green                                                                          (Munsell code)                                                                       5GY48                                       1.0       Bar Glumes (Glume Bands): 1 = Absent 2 = Present                    6a.                                                                             EAR (Unhusked Data):                                                        1         Silk Color (3 days after emergence)                                                                Light Green                                                                         (Munsell code)                                                                       2.5GY76                           1         Fresh Husk Color (25 days after 50% silking)                                                       Light Green                                                                         (Munsell code)                                                                       5GY56                             21        Dry Husk Color (65 days after 50% silking)                                                         Buff  (Munsell code)                                                                       2.5Y92                            1         Position of Ear at Dry Husk Stage: 1 = Upright 2 = Horizontal                 3 = Pendant                         Upright                         5.5       Husk Tightness (Rate of Scale from 1 = very loose to 9 = very                 tight)                                                              2         Husk Extension (at harvest): 1 = Short (ears exposed) 2 =                     Medium (<8 cm)                                                                3 = Long (8-10 cm beyond ear tip) 4 = Very Long (>10                                                              Medium                          6b.                                                                             EAR (Husked Ear Data):                                                                                                Standard                                                                           Sample                                                                   Deviation                                                                          Size                              19.2                                                                             cm  Ear Length                      2.5455                                                                             10                                44.6                                                                             mm  Ear Diameter at mid-point       4.2426                                                                             10                               196.                                                                              gm  Ear Weight                      87.539                                                                             10                                14     Number of Kernel Rows           1.1313                                                                             10                                2      Kernel Rows: 1 = Indistinct 2 = Distinct   Distinct                    1      Row Alignment: 1 = Straight 2 = Slightly Curved 3                                                                        Straight                    11.7                                                                             cm  Shank Length                    2.9698                                                                             10                                2      Ear Taper: 1 = Slight 2 = Average 3 = Extreme                                                                            Average                  7.                                                                              KERNEL (Dried):                                                                                                       Standard                                                                           Sample                                                                   Deviation                                                                          Size                           12.6  mm  Kernel Length                   1.1313                                                                             10                             8.4   mm  Kernel Width                    8.5924                                                                             10                             4.2   mm  Kernel Thickness                4.2962                                                                             10                             6.37      % Round Kernels (Shape Grade)   0.5600                                                                             2                              1         Aleurone Color Pattern: 1 = Homozygous 2 = Segregating                                                                   Homozygous               8         Aluerone Color                                                                          Yellow-Orange                                                                        (Munsell code)                                                                       10YR814                                     7         Hard Endosperm Color                                                                    Yellow (Munsell code)                                                                       2.5Y8.512                                   3         Endosperm Type:                                                                         Normal Starch                                                       1 = Sweet (Su1) 2 = Extra Sweet (sh2) 3 = Normal Starch                       4 = High Amylose Starch 5 = Waxy Starch 6 = High Protein                      7 = High Lysine 8 = Super Sweet (se) 9 = High Oil                             10 = Other                                                          30    gm  Weight per 100 Kernels (unsized sample)                                                                       5.6568                                                                             2                              8.                                                                              COB:                                                                                                                  Standard                                                                           Sample                                                                   Deviation                                                                          Size                           21.6  mm  Cob Diameter at mid-point       2.2627                                                                             10                             11        Cob Color Pink   (Munsell code)                                                                       10R84                                       2         Cob Strength 1 = Weak 2 = Strong                                    9.                                                                              DISEASE RESISTANCE (Rate from 1 (most susceptible) to 9 (most                 resistant); leave blank                                                       if not tested; leave Race or Strain Options blank if polygenic):           A.        Leaf Blights, Wilts, and Local Infection Diseases                             Anthracnose Leaf Blight (Colletotrichum graminicola)                          Common Rust (Puccinia sorghi)                                                 Common Smut (Ustilago maydis)                                                 Eyespot (Kabatiella zeae)                                                8    Goss's Wilt (Clavibacter michiganense spp. nebreskense)                  5    Gray Leaf Spot (Cercospora zeae-maydis)                                       Helminthosporium Leaf Spot (Bipolaris zeicola)                           5    Northern Leaf Blight (Exserohilum turcicum)                              6    Southern Leaf Blight (Bipolaris maydis)                                  3.5  Southern Rust (Puccinia polysora)                                        3    Stewart's Wilt (Erwinia stewartii)                                            Other (Specify)                                                     B.        Systemic Diseases                                                        7    Corn Lethal Necrosis (MCMV and MDMV)                                          Head Smut (Sphacelotheca reiliana)                                            Maize Chlorotic Dwarf Virus (MDV)                                             Maize Chlorotic Mottle Virus (MCMV)                                      4    Maize Dwarf Mosaic Virus (MDMV)                                               Sorghum Downy Mildew of Corn (Peronosclerospora sorghi)                       Other (Specify)                                                     C.        Stalk Rots                                                               3    Anthracnose Stalk Rot (Colletotrichum graminicola)                            Dipiodia Stalk Rot (Stenocarpella maydis)                                     Fusarium Stalk Rot (Fusarium moniliforme)                                     Gibberella Stalk Rot (Gibberella zeae)                                        Other (Specify)                                                     D         Ear and Kernel Rots                                                           Aspergillus Ear and Kernel Rot (Aspergillus flavus)                           Diplodia Ear Rot (Stenocarpella maydis)                                  5    Fusarium Ear and Kernel Rot (Fusarium moniliforme)                            Gibberella Ear Rot (Gibberella zeae)                                          Other (Specify)                                                     10.                                                                              INSECT RESISTANCE (Rate from 1 (most susceptible) to 9 (most                  resistant);                                                                   (leave blank if not tested)                                                          Banks grass Mite (Oligonychus pratensis)                                      Corn Worm (Helicoverpa zea)                                                   Leaf Feeding                                                                  Silk Feeding                                                                  mg larval wt.                                                                 Ear Damage                                                                    Corn Leaf Aphid (Rhopalosiphum maidis)                                        Corn Sap Beetle (Carpophilus dimidiatus)                                      European Corn Borer (Ostrinia nubilalis)                                 4.9  1st Generation (Typically Whorl Leaf Feeding)                            5.7  2nd Generation (Typically Leaf Sheath-Collar Feeding)                         Stalk Tunneling                                                          2.4  cm tunneled/plant                                                             Fall Armyworm (Spodoptera fruqiperda)                                         Leaf Feeding                                                                  Silk Feeding                                                                  mg larval wt.                                                                 Maize Weevil (Sitophilus zeamaize)                                            Northern Rootworm (Diabrotica barberi)                                        Southern Rootworm (Diabrotica undecimpunctata)                                Southwestern Corn Borer (Diatreaea grandiosella)                              Leaf Feeding                                                                  Stalk Tunneling                                                               cm tunneled/plant                                                             Two-spotted Spider Mite (Tetranychus urticae)                                 Western Rootworm (Diabrotica virgifrea virgifera)                             Other (Specify)                                                        AGRONOMIC TRAITS:                                                          5         Staygreen (at 65 days after anthesis) (Rate on a scale from 1 =               worst to                                                                      excellent)                                                          0.2       % Dropped Ears (at 65 days after anthesis)                                    % Pre-anthesis Brittle Snapping                                               % Pre-anthesis Root Lodging                                         1.6       Post-anthesis Root Lodging (at 65 days after anthesis)              10,980    Kg/ha Yield (at 12-13% grain moisture)                              __________________________________________________________________________

Research Comparisons for Pioneer Hybrid 3237

Comparisons of characteristics for Pioneer Brand Hybrid 3237 were madeagainst Pioneer Brand Hybrids 3162, 3225 and 3245.

Table 2A compares Pioneer Hybrid 3237 and Pioneer Hybrid 3162. Theresults show that Hybrid 3237 is significantly higher yielding thanHybrid 3162. While both hybrids demonstrate above average resistance toroot lodging and above average resistance to brittle stalk, Hybrid 3237demonstrates better resistance to Corn Lethal Necrosis and betterresistance to Gray Leaf Spot than Hybrid 3162. Hybrid 3237 alsodemonstrates better early stand count than Hybrid 3162.

Table 2B compares Pioneer Hybrid 3237 and Pioneer Hybrid 3225. Theresults show that Hybrid 3237 is significantly higher yielding thanHybrid 3225. While both hybrids demonstrate good resistance to brittlestalk and good resistance to Corn Lethal Necrosis, Hybrid 3237demonstrates better resistance to root lodging, Gray Leaf Spot, SouthernLeaf Blight and Southern Rust than Hybrid 3225. Hybrid 3237 alsodemonstrates significantly better early stand count and betterresistance to stalk lodging than Hybrid 3225.

Table 2C compares Pioneer Hybrid 3237 and Pioneer Hybrid 3245. Theresults show that while both hybrids are above average yielding and bothdemonstrate above average resistance to brittle stalk, Hybrid 3237demonstrates better resistance to root lodging than Hybrid 3245. Hybrid3237 demonstrates better resistance to Gibberella Ear Rot than Hybrid3245. Hybrid 3237 also demonstrates better early stand count and betterresistance to Gray Leaf Spot than Hybrid 3245.

                                      TABLE 2A                                    __________________________________________________________________________    VARIETY #1 = 3237                                                             VARIETY #2 = 3162                                                             __________________________________________________________________________                   PRM BU  BU      TST SDG EST GDU                                           PRM SHD ACR ACR MST WT  VGR CNT SHD                                           ABS ABS ABS % MN                                                                              % MN                                                                              ABS % MN                                                                              % MN                                                                              % MN                               __________________________________________________________________________    TOTAL SUM                                                                            1   116 115 175.7                                                                             105 105 56.8                                                                              94  105 103                                       2   118 111 168.3                                                                             100 110 57.1                                                                              104 103 99                                        LOCS                                                                              24  28  139 139 143 79  52  64  34                                        REPS                                                                              24  28  202 202 206 92  67  74  45                                        DIFF                                                                              2   3   7.3 5   5   0.3 10  2   4                                         PR > T                                                                            .000#                                                                             .000#                                                                             .000#                                                                             .000#                                                                             .000#                                                                             .090*                                                                             .001#                                                                             .040+                                                                             .000#                              __________________________________________________________________________               GDU STK PLT EAR RT  STA STK BRT GRN                                           SLK CNT HT  HT  LDG GRN LDG STK APP                                           % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                               __________________________________________________________________________    TOTAL SUM                                                                            1   103 102 94  95  106 105 101 107 98                                        2   101 101 95  92  104 104 101 106 103                                       LOCS                                                                              20  157 66  65  50  46  95  19  15                                        REPS                                                                              22  232 87  85  77  65  135 28  15                                        DIFF                                                                              2   1   1   3   3   1   1   0   4                                         PR > T                                                                            .000#                                                                             .136                                                                              .018+                                                                             .001#                                                                             .225                                                                              .829                                                                              .572                                                                              .999                                                                              .399                               __________________________________________________________________________               DRP GLF NLF SLF GOS STW ANT HD                                                EAR SPT BLT BLT WLT WLT ROT SMT CLN                                           % MN                                                                              ABS ABS ABS ABS ABS ABS ABS ABS                                __________________________________________________________________________    TOTAL SUM                                                                            1   100 5.0 4.7 4.6 8.0 3.0 3.3 95.6                                                                              6.5                                       2   100 2.7 3.9 3.1 7.5 4.0 3.1 98.6                                                                              4.5                                       LOCS                                                                              31  12  6   4   1   1   7   3   2                                         REPS                                                                              36  20  12  8   2   2   12  6   4                                         DIFF                                                                              0   2.3 0.8 1.5 0.5 1.0 0.1 3.0 2.0                                       PR > T                                                                            .999                                                                              .000#                                                                             .165                                                                              .190        .604                                                                              .423                                                                              .295                               __________________________________________________________________________               MDM FUS GIB COM SOU ECB ECB ECB ECB                                           CPX ERS ERS RST RST DPE 1LF 2SC 2IT                                           ABS ABS ABS ABS ABS ABS ABS ABS ABS                                __________________________________________________________________________    TOTAL SUM                                                                            1   3.5 4.9 7.0 6.0 3.7 100.0                                                                             4.9 5.2 2.4                                       2   2.8 6.0 7.0 5.0 3.7 100.0                                                                             3.2 5.1 0.5                                       LOCS                                                                              2   4   1   1   3   3   3   15  1                                         REPS                                                                              6   7   1   2   5   5   7   23  3                                         DIFF                                                                              0.8 1.1 0.0 1.0 0.0 0.0 1.7 0.1 1.9                                       PR > T                                                                            .205                                                                              .328        .999                                                                              .999                                                                              .073*                                                                             .754                                   __________________________________________________________________________     * = 10% SIG                                                                   + = 5% SIG                                                                    # = 1% SIG                                                               

                                      TABLE 2B                                    __________________________________________________________________________    VARIETY #1 = 3237                                                             VARIETY #2 = 3225                                                             __________________________________________________________________________                   PRM BU  BU      TST SDG EST GDU                                           PRM SHD ACR ACR MST WT  VGR CNT SHD                                           ABS ABS ABS % MN                                                                              % MN                                                                              ABS % MN                                                                              % MM                                                                              % MN                               __________________________________________________________________________    TOTAL SUM                                                                            1   115 115 166.1                                                                             105 106 56.6                                                                              92  105 103                                       2   115 111 159.5                                                                             101 106 56.9                                                                              97  98  99                                        LOCS                                                                              32  27  154 154 159 88  42  71  33                                        REPS                                                                              32  27  194 194 199 101 49  80  42                                        DIFF                                                                              0   4   6.6 4   0   0.3 5   6   4                                         PR > T                                                                            .999                                                                              .000#                                                                             .000#                                                                             .000#                                                                             .999                                                                              .058*                                                                             .177                                                                              .000#                                                                             *000#                              __________________________________________________________________________               GDU STK PLT EAR RT  STA STK BRT GRN                                           SLK CNT HT  HT  LDG GRN LDG STK APP                                           % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                               __________________________________________________________________________    TOTAL SUM                                                                            1   103 103 95  95  107 104 101 106 97                                        2   100 100 96  95  99  98  100 106 115                                       LOCS                                                                              19  175 75  74  58  32  83  20  14                                        REPS                                                                              21  228 92  90  71  46  106 27  14                                        DIFF                                                                              3   3   2   0   9   5   2   0   18                                        PR > T                                                                            .000#                                                                             .000#                                                                             .001#                                                                             .999                                                                              .005#                                                                             .476                                                                              .027+                                                                             .999                                                                              .116                               __________________________________________________________________________               DRP GLF NLF SLF GOS STW ANT HD                                                EAR SPT BLT BLT WLT WLT ROT SMT CLN                                           % MN                                                                              ABS ABS ABS ABS ABS ABS ABS ABS                                __________________________________________________________________________    TOTAL SUM                                                                            1   100 5.1 4.3 5.3 8.0 3.0 3.1 100.0                                                                             6.5                                       2   100 2.3 4.3 3.2 8.0 4.5 2.5 100.0                                                                             6.5                                       LOCS                                                                              36  8   3   3   1   1   4   1   1                                         REPS                                                                              40  12  6   6   2   2   8   2   2                                         DIFF                                                                              0   2.8 0.0 2.2 0.0 1.5 0.6 0.0 0.0                                       PR > T                                                                            .999                                                                              .000#                                                                             .999                                                                              .006#       .194                                       __________________________________________________________________________                   MDM FUS COM SOU ECB ECB ECB ECB                                               CPX ERS RST RST DPE 1LF 2SC 21T                                               ABS ABS ABS ABS ABS ABS ABS ABS                                __________________________________________________________________________    TOTAL SUM  1   3.5 5.0 6.0 3.7 100.0                                                                             4.3 4.7 2.4                                           2   3.0 4.8 4.5 2.7 99.3                                                                              2.3 4.1 0.8                                           LOCS                                                                              1   2   1   3   3   1   11  1                                             REPS                                                                              4   4   2   5   5   3   13  3                                             DIFF                                                                              0.5 0.3 1.5 1.0 0.7 2.0 0.6 1.6                                           PR > T  .500    .000#                                                                             .423    .221                                   __________________________________________________________________________     * = 10% SIG                                                                   + = 5% SIG                                                                    # = 1% SIG                                                               

                                      TABLE 2C                                    __________________________________________________________________________    VARIETY #1 = 3237                                                             VARIETY #2 = 3245                                                             __________________________________________________________________________                   PRM BU  BU      TST SDG EST GDU                                           PRM SHD ACR ACR MST WT  VGR CNT SHD                                           ABS ABS ABS % MN                                                                              % MN                                                                              ABS % MN                                                                              % MN                                                                              % MN                               __________________________________________________________________________    TOTAL SUM                                                                            1   116 115 170.9                                                                             104 104 56.9                                                                              96  103 102                                       2   114 114 169.1                                                                             102 99  58.7                                                                              102 101 101                                       LOCS                                                                              33  29  176 176 181 80  72  75  39                                        REPS                                                                              33  29  236 236 241 96  90  86  50                                        DIFF                                                                              2   1   1.8 1   5   1.8 6   2   1                                         PR > T                                                                            .000#                                                                             .030+                                                                             .325                                                                              .190                                                                              .000#                                                                             .000#                                                                             .037+                                                                             .034+                                                                             .014+                              __________________________________________________________________________               GDU STK PLT EAR RT  STA STK BRT GRN                                           SLK CNT HT  HT  LDG GRN LDG STK APP                                           % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                               __________________________________________________________________________    TOTAL SUM                                                                            1   102 102 93  94  110 103 98  106 99                                        2   102 101 100 96  100 96  100 105 103                                       LOCS                                                                              23  194 75  74  77  58  124 23  28                                        REPS                                                                              25  267 86  84  114 69  172 32  28                                        DIFF                                                                              1   1   6   2   9   7   1   1   4                                         PR > T                                                                            .112                                                                              .219                                                                              .000#                                                                             .067*                                                                             .065*                                                                             .199                                                                              .170                                                                              .650                                                                              .141                               __________________________________________________________________________               DRP GLF NLF MDM GIB ECB ECB ECB ECB                                           EAR SPT BLT CPX ERS DPE 1LF 2SC 21T                                           % MN                                                                              ABS ABS ABS ABS ABS ABS ABS ABS                                __________________________________________________________________________    TOTAL SUM                                                                            1   100 5.3 5.0 3.5 7.5 100.0                                                                             4.3 5.5 2.4                                       2   100 4.5 3.4 3.0 5.0 98.1                                                                              2.0 5.2 1.1                                       LOCS                                                                              36  6   2   2   1   2   1   17  1                                         REPS                                                                              41  6   5   4   2   4   3   24  3                                         DIFF                                                                              0   0.8 1.6 0.5 2.5 1.9 2.3 0.3 1.3                                       PR > T                                                                            .999                                                                              .042+                                                                             .118                                                                              .500    .500    .509                                   __________________________________________________________________________     * = 10% SIG                                                                   + = 5% SIG                                                                    # = 1% SIG                                                               

Strip Test Data for Hybrid 3237

Comparison data was collected from strip tests that were grown byfarmers. Each hybrid was grown in strips of 4, 6, 8, 12, etc. rows infields depending on the size of the planter used. The data was collectedfrom strip tests that had the hybrids in the same area and weighed. Themoisture percentage was determined and bushels per acre was adjusted to15.5 percent moisture. The number of comparisons represent the number oflocations or replications for the two hybrids that were grown in thesame field in close proximity and compared.

Comparison strip testing was done between Pioneer Brand Hybrid 3237 andPioneer Brand Hybrids 3162, 3225 and 3245. The comparisons come from allthe hybrid's adapted growing areas in the United States.

These results are presented in Table 3. Hybrid 3237 has a 1.5 bushel peracre yield advantage and a $6.81 per acre income advantage over 3162.Hybrid 3237 has a 0.1 bushel per acre yield advantage and a $1.37 preacre income advantage over 3225. Hybrid 3237 has a 3.1 bushel per acreand a $3.17 per acre income advantage over 3245. Hybrid 3237 has aweighted average 1.0 bushel per acre yield advantage and a weightedadvantage and a weighted average $3.94 per acre income advantage overthe other hybrids. Hybrid 3237 also has a weighted average 0.4percentage point moisture advantage and a weighted average 1.0percentage point root advantage over the other hybrids.

                                      TABLE 3                                     __________________________________________________________________________    1995 PERFORMANCE COMPARISON REPORT FOR CORN                                   1 YEAR SUMMARY OF ALL STANDARD TEST TYPES.                                                         Income/                                                                           Pop Stand                                                                            Roots                                                                             Test                                      Brand      Product                                                                           Yield                                                                            Moist                                                                            Acre                                                                              K/Acre                                                                            (%)                                                                              (%) Wt                                        __________________________________________________________________________    PIONEER    3237                                                                              158.2                                                                            19.4                                                                             382.36                                                                            26.0                                                                              90 98  56.7                                      PIONEER    3162                                                                              156.7                                                                            20.5                                                                             375.55                                                                            26.0                                                                              92 97  56.9                                      Advantage      1.5                                                                              1.1                                                                              6.81                                                                              0.0 -2 1   -0.2                                      Number of Comparisons                                                                        283                                                                              283                                                                              283 109 75 49  260                                       Percent Wins   59 79 65  37  38 4   32                                        Probability of Difference                                                                    88 99 99  30  84 58  98                                        PIONEER    3237                                                                              156.7                                                                            19.5                                                                             378.47                                                                            26.1                                                                              91 92  56.6                                      PIONEER    3225                                                                              156.6                                                                            19.9                                                                             377.10                                                                            25.8                                                                              89 91  56.8                                      Advantage      0.1                                                                              0.4                                                                              1.37                                                                              0.3 2  1   -0.2                                      Number of Comparisons                                                                        291                                                                              291                                                                              291 115 79 55  283                                       Percent Wins   51 59 52  47  46 3   30                                        Probability of Difference                                                                    9  99 48  83  74 78  99                                        PIONEER    3237                                                                              148.8                                                                            19.5                                                                             358.87                                                                            25.6                                                                              95 100 57.3                                      PIONEER    3245                                                                              145.7                                                                            17.7                                                                             355.70                                                                            25.7                                                                              95 97  58.8                                      Advantage      3.1                                                                              -1.8                                                                             3.17                                                                              -0.1                                                                              0  3   -1.5                                      Number of Comparisons                                                                        85 85 85  28  25 23  64                                        Percent Wins   64 8  56  35  36 21  9                                         Probability of Difference                                                                    96 99 60  28  45 86  99                                        PIONEER    3237                                                                              156.3                                                                            19.5                                                                             377.61                                                                            26.0                                                                              91 96  56.7                                      WEIGHTED AVG   155.3                                                                            19.9                                                                             373.67                                                                            25.9                                                                              91 95  57.0                                      Advantage      1.0                                                                              0.4                                                                              3.94                                                                              0.1 0  1   -0.3                                      Number of Comparisons                                                                        659                                                                              659                                                                              659 252 179                                                                              127 607                                       Percent Wins   56 61 58  42  41 7   29                                        Probability of Difference                                                                    93 99 99  74  1  96  99                                        __________________________________________________________________________     NOTE:                                                                         The probability values are useful in analyzing if there is a "real"           difference in the genetic potential of the products involved. High values     are desirable, with 95% considered significant for real differences.     

Comparison of Key Characteristics for Hybrid 3237

Characteristics of Pioneer Hybrid 3237 are compared to Pioneer Hybridsin Table 4. The values given for most of the traits are on a 1-9 basis.In these cases 9 would be outstanding, while 1 would be poor for thegiven characteristics. These values are based on performance of a givenhybrid relative to other Pioneer commercial, precommercial andcompetitive hybrids that are grown in research strip test trials. Theseperformance based values are determined utilizing several factors suchas research data, experience the trained corn researchers had in thefield, and the sales experience with the hybrids in strip tests in thefield. These values reflect the hybrid's relative performance to otherhybrids for the characteristics listed. Table 4 shows Hybrid 3237 ishigh yielding under normal plant density, high plant density and lowplant density environments. Hybrid 3237 also demonstrates very goodresistance to root lodging and very good resistance to brittle stalk.Hybrid 3237 demonstrates good drought tolerance and a very good proteinyield rating.

                                      TABLE 4                                     __________________________________________________________________________    Hybrid Patent Comparisons-Characteristics                                     Pioneer Hybrid 3237 vs. Pioneer Hybrids 3162, 3225 and 3245                   __________________________________________________________________________            SILK                                                                             PHY                                                                              GDU                                                                              GDU                                                          VARIETY                                                                            CRM                                                                              CRM                                                                              CRM                                                                              SILK                                                                             PHY                                                                              YLD                                                                              H/POP                                                                             L/POP                                                                             D/D                                                                              S/L                                                                              R/L                                      __________________________________________________________________________    3237 116                                                                              114                                                                              115                                                                              1420                                                                             2800                                                                             9  9   8   5  5  8                                        3162 118                                                                              112                                                                              114                                                                              1400                                                                             2770                                                                             9  9   8   3  5  7                                        3225 115                                                                              113                                                                              113                                                                              1410                                                                             2750                                                                             9  9   8   5  4  5                                        3245 115                                                                              115                                                                              114                                                                              1440                                                                             2770                                                                             8  7   8   6  5  4                                        __________________________________________________________________________         STA    TST    PLT EAR    BRT                                             VARIETY                                                                            GRN D/T                                                                              WT  E/G                                                                              HT  HT D/E STK                                                                              PRO P/Y                                      __________________________________________________________________________    3237 5   7  5   4  3   4  5   8  5   9                                        3162 5   7  7   6  3   3  5   7  4   8                                        3225 4   7  6   5  3   4  5   8  4   8                                        3245 5   5  8   5  6   4  5   6  6   9                                        __________________________________________________________________________

INDUSTRIAL APPLICABILITY

This invention includes hybrid maize seed of 3237 and the hybrid maizeplant produced therefrom. The foregoing was set forth by way of exampleand is not intended to limit the scope of the invention.

As used herein, the term plant includes plant cells, plant protoplasts,plant cell tissue cultures from which maize plants can be regenerated,plant calli, plant clumps, and plant cells that are intact in plants, orparts of plants, such as embryos, pollen, ovules, flowers, kernels,ears, cobs, leaves, seeds, husks, stalks, roots, root tips, anthers,silk and the like.

Duncan, Williams, Zehr, and Widholm, Planta, (1985) 165:322-332 reflectsthat 97% of the plants cultured which produced callus were capable ofplant regeneration. Subsequent experiments with both inbreds and hybridsproduced 91% regenerable callus which produced plants. In a furtherstudy in 1988, Songstad, Duncan & Widholm in Plant Cell Reports (1988),7:262-265 reports several media additions which enhance regenerabilityof callus of two inbred lines. Other published reports also indicatedthat "nontraditional" tissues are capable of producing somaticembryogenesis and plant regeneration. K. P. Rao, et al., Maize GeneticsCooperation Newsletter, 60:64-65 (1986), refers to somatic embryogenesisfrom glume callus cultures and B. V. Conger, et al., Plant Cell Reports,6:345-347 (1987) indicates somatic embryogenesis from the tissuecultures of maize leaf segments. Thus, it is clear from the literaturethat the state of the art is such that these methods of obtaining plantsare, and were, "conventional" in the sense that they are routinely usedand have a very high rate of success.

Tissue culture of maize is described in European Patent Application,publication 160,390, incorporated herein by reference. Maize tissueculture procedures are also described in Green and Rhodes, "PlantRegeneration in Tissue Culture of Maize," Maize for Biological Research(Plant Molecular Biology Association, Charlottesville, Va. 1982, at367-372) and in Duncan, et al., "The Production of Callus Capable ofPlant Regeneration from Immature Embryos of Numerous Zea MaysGeneotypes," 165 Planta 322-332 (1985). Thus, another aspect of thisinvention is to provide cells which upon growth and differentiationproduce maize plants having the genotype of 3237.

Maize is used as human food, livestock feed, and as raw material inindustry. The food uses of maize, in addition to human consumption ofmaize kernels, include both products of dry- and wet-milling industries.

Maize, including both grain and non-grain portions of the plant, is alsoused extensively as livestock feed, primarily for beef cattle, dairycattle, hogs, and poultry.

Industrial uses of maize include production of ethanol, maize starch inthe wet-milling industry and maize flour in the dry-milling industry.The industrial applications of maize starch and flour are based onfunctional properties, such as viscosity, film formation, adhesiveproperties, and ability to suspend particles. The maize starch and flourhave application in the paper and textile industries. Other industrialuses include applications in adhesives, building materials, foundrybinders, laundry starches, explosives, oil-well muds, and other miningapplications.

Plant parts other than the grain of maize are also used in industry.Stalks and husks are made into paper and wallboard and cobs are used forfuel and to make charcoal.

The seed of the hybrid maize plant and various parts of the hybrid maizeplant can be utilized for human food, livestock feed, and as a rawmaterial in industry.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity andunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the invention, as limited only bythe scope of the appended claims.

Applicant has made a deposit of at least 2500 seeds of Hybrid Maize Line3237 with the American Type Culture Collection (ATCC), Rockville, Md.20852 USA, ATCC Deposit No. 209500. The seeds deposited with the ATCC onNov. 25, 1997 were taken from the deposit maintained by Pioneer Hi-BredInternational, Inc., 700 Capital Square, 400 Locust Street, Des Moines,Iowa 50309-2340 since prior to the filing date of this application. Thisdeposit of the Hybrid Maize Line 3237 will be maintained in the ATCCdepository, which is a public depository, for a period of 30 years, or 5years after the most recent request, or for the enforceable life of thepatent, whichever is longer, and will be replaced if it becomesnonviable during that period. Additionally, Applicant has satisfied allthe requirements of 37 C.F.R §§1.801-1.809, including providing anindication of the viability of the sample. Applicant imposes norestrictions on the availability of the deposited material from theATCC; however, Applicant has no authority to waive any restrictionsimposed by law on the transfer of biological material or itstransportation in commerce. Applicant does not waive any infringement ofits rights granted under this patent.

I claim:
 1. Hybrid maize seed designated 3237, representative seed ofsaid hybrid 3237 having been deposited under ATCC accession number209500.
 2. A maize plant, or its parts, produced by the seed of claim 1.3. Pollen of the plant of claim
 2. 4. An ovule of the plant of claim 2.5. A tissue culture of regenerable cells of a hybrid maize plant 3237,representative seed of said hybrid maize plant 3237 having beendeposited under ATCC accession number 209500, wherein the tissueregenerates plants capable of expressing all the morphological andphysiological characteristics of said hybrid maize plant
 3237. 6. Atissue culture according to claim 5, the cells or protoplasts being of atissue selected from the group consisting of leaves, pollen, embryos,roots, root tips, anthers, silks, flowers, kernels, ears, cobs, husks,and stalks.
 7. A maize plant, or its parts, regenerated from the tissueculture of claim 5 and capable of expressing all the morphological andphysiological characteristics of hybrid maize plant 3237, representativeseed having been deposited under ATCC accession number 209500.